1. Field of the Invention
The present invention relates to a feeding device for printed products including a conveyor for conveying the printed products on a front conveying section in the form of a stack and on a rear conveying section in the form of a bar and in the form of a loosened zone between the stack and the bar, and a sensing device which senses the position of the stack and controls the feeding movement of the printed products.
2. Description of the Related Art
A device of the above-described type is disclosed in Swiss Patent No. 584,642. This device has been found useful in practice as a feeding mechanism for a feeder for a gathering machine.
In the known device, a tip senses the position of the stack and controls the feeding movement of the printed products in this manner. The feeding movement is effected through eccentric members or cams which must be of very robust construction because the paper to be moved during feeding may have a high weight of 200 to 300 kg.
For some time, there has now been a demand for a higher feeding speed which should exceed about 24,000 units per hour. However, at such high speeds, the mechanical load cannot be controlled in the case of thick printed products. Also, due to the different compressibility of the paper in the bars and when removing an end plate, differences occur in the feeding movements between stack and bar. It is possible to partially compensate these differences by a mechanical transmission into slow or fast feeding movements of intermediate stack and bar. However, if this transmission is not precisely adjusted to the type of paper, problems may occur. These problems may be that the bar can sink or the pressure in the stack becomes so high that the operation of the feeder is no longer ensured. In addition, it is desirable that such a device can also be used for very thick products having, for example, 96 or more pages, as well as for extremely thin four-page sheets.